mapPropsOnUpdate add childProps to propsMapper call about recompose

[acdlite]

mapPropsOnUpdate() is just a shortcut for compose(shouldUpdate(...), mapProps(...)). If you want more control over when to update, use that.

[istarkov]

It's not compose of shouldUpdate and mapProps
component may update and not recalculate some internal values.

Your code for mapPropsOnUpdate does not contain any shouldComponentUpdate calls.

And there is no method like
mapPropsOnUpdate(props => myCompareFn, props => newProps)

[acdlite]

Ah you're right, clearly I don't know my own library well enough :)

Let me think about this one for a bit.

[acdlite]

I know the implementation is slightly different, but is there any reason why compose(shouldUpdate(...), mapProps(...)) wouldn't achieve the desired effect?

[istarkov]

I need to redraw but not to call again some intensive calculate function.
And in redraw i need result of that function.
And if some props changed, i need to run calculate function again after some additional checks.

Animation - in my current task.
I have map with svg tiles over it.
Instead of full svg path points position recalculation i can use css transforms until some props changes.

For example i scale on zoom oversimplified map tiles until tiles for new zoom level arrived.
Tiles preparation for swg drawing is really intensive task.
Also I can't call recalculate until google map stop animation (otherwise it breaks animation)

So i check shallow equality on some props inside componentWillReceiveProps,
and if it false I make additional checks - could i reuse previous calculation partially or need to make full recalc again.

But I need to react on other props changes.

It's something like reduce operation - take some new data, take previous result and create something new if needed.

[acdlite]

I have a mostly-finished withReducer() helper that I'll push soon. I think it may address your issue.

[istarkov]

Thank you!!!
recompose is really fun library.

[acdlite]

Closed by #10

[istarkov]

In combination with doOnReceiveProps as like as I need
withReducer will cause Warning: setState(...): Cannot update during an existing state transition (such as within render).

Because of call to some parent setState inside child constructor.

Calls actions inside componentWillReceiveProps are OK but gives additional render.

IMHO this withReducer is good for most situations except mine.

All I need is this.

const createReduce = (reducer, BaseComponent) => (
  class Reduce extends React.Component {
    static displayName = wrapDisplayName(BaseComponent, 'Reduce');

    constructor(props, context) {
      super(props, context);
      this.memo_ = reducer(undefined, props);
    }

    componentWillReceiveProps(nextProps) {
      this.memo_ = reducer(this.memo_, nextProps);
    }

    render() {
      return <BaseComponent {...this.props} {...this.memo_} />;
    }
  }
);